I recently used this example from the Cookbook which worked very well for me...
(There are other methods in the book so it's a highly recommended resource): 
%seen = ();
@uniq = ();
foreach $item (@list) {
    unless ($seen{$item})  {
        # if we get here, we have not seen it before
        $seen{$item} = 1;
        push(@uniq, $item);
    }
}

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Update: Inserted missed bracket spotted by Martymart

In reply to Re: finding unique elements in an array by jonnyfolk
in thread finding unique elements in an array by Anonymous Monk

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